There are two rooms at the disposal of those reporting from South by Southwest (SXSW). Both have grey canvas walls and a watercooler, and are on the top floor of the Austin Convention Centre (think Kubrick does Comfort Inn). To enter the press suite you need to have been previously OKed by the press officer and to work for an approved media organisation. To gain access to the blogger lounge, all you need is your festival pass (anybody's, for a fee), and to register your email address. A blog is not a requirement.

So guess which one is light and spacious, with lush carpets and a fleet of iPads, a free bar, popcorn, hot snacks, live music and keynote speakers? And which one feels a bit like working inside a filing cabinet? The press suite does have complimentary coffee, a sporadic cheese platter and helpful staff. But there's little doubt which set of writers has been identified as the better bet to butter up.

From the moment you set foot in SXSW, it's evident you're teetering on a tipping point in the democratisation of the film universe. Cinema may be the least important of the festival's three strands (the others being music and interactive), but both the types of film that predominate at SXSW – genre-savvy geek movies and low-budget indie flicks – are in their own ways representative of the digital revolution, and indicative of what may happen next.

Geek movies rule the roost, partly because their consumers are so omnipresent: the thick-set, dense-bearded, logo T-shirted, hooting, whooping, white, apparently heterosexual thirtysomethings with fingers locked to keypad. Someone once told me that when they used to lecture in a women's college in America in the 50s, his words were barely audible over all the knitting. At SXSW, it's tapping – even smartphones, in such quantity, can be surprisingly clattery.

Directors of genre films love premiering here because these lads are, in the words of British director Joe Cornish – whose comedy horror Attack the Block was lapped up – "film champions, rather than film critics. If they don't like something, they just won't write about it."

It's not news that directors love non-sceptical flattery. But don't underestimate the power of bloggers pleading the fifth. It's a symbiotic relationship – because he's now a publisher, too, the fanboy is the tastemaker. And if he doesn't write about your film, it exists a little less.

Nor is it news that, as professional critics dwindle, power has passed to audiences. But it's not just audiences in general. It is the most energetic members who dominate, because it's not just headcount that matters, but the will to participate. So it's exactly that noisy tapping that enables the fanboy to shape the future in his image.

Some of the sites they produce are terrific; others simply in-joke backchat. "I don't see reviews as consumer reports," said Devin Faraci, editor of Badass Digest, "but hopefully as something that will spark a discussion." Faraci was speaking at a panel called You Are Not a Publicist: Criticism vs Advertising, whose very conceit would have been laughable just a few years back. Now where to draw the line is a genuine concern for this new breed of reporters. Anne Thompson's site, Thompson on Hollywood, straddles the space between trade papers such as Variety and the Hollywood Reporter and lighter-touch blogs. "The people who write them would rankle at being called fansites, but they aren't journalists," she says. "And yet they're increasingly getting the scoops. Their leverage with studios comes from providing a direct line between the films and the fans."

So it's not just the journalist who could be out of a job; it's the publicist, too. Traditional marketing is collapsing – not merely because of costs, but because commercial activity is distrusted. Viral buzz, on the other hand, feeds specific tastes by being more precise, and because it caters to the growing hunger for participation – the "demand this" mentality where people power can change multiplex managers' minds about what they screen. The more homemade the advance word on your film, cooked up by the audience itself for no money, the better.

So: fanboys affect the perception of what has been made. But they also affect cinema itself, warping the nature of what's produced. Depending on your tastes, that either means people are finally getting what they want, or that mainstream creativity is diverted into repetitive self-indulgence, often involving aliens, at the expense of genuine innovation.

And partly because these people are in the business because of their interest in film, rather than in reporting, they're very responsive to the courtship of their idols. At the top of the geek tree is Harry Knowles, founder of Ain't It Cool News, the Austin-based site that specialises in enthusiastic unpicking of upcoming fanboy fare, early buzz from advance screenings and (rarer in this world) lavish trashings of turkeys (the site first hit headlines after a review of Joel Schumacher's Batman & Robin). Knowles's clout has endeared him to his heroes: Guillermo del Toro is "like a brother", Tarantino is on speed-dial. Knowles even had a bit part in Robert Rodriguez's The Faculty.

Knowles, though, is the exception; a man whose savvy prose and basic charisma is what sets his site apart. And it's worth remembering that he set it up out of necessity, not unadulterated passion, 15 years ago, two weeks after an accident that left him paralysed. "I was terrified that I would never leave an impact on the world. I wanted to do something from my bedroom that I could get paid for. And I knew it wasn't gonna be sex."

At the other end of the spectrum, too, in the world of low-budget indie dramas and documentaries, SXSW shows the slackening grip of the elite on what gets greenlit. The nurturing of self-expression, as well as the collapse of the cost of entry into this world through the advent of digital cameras, means self- and crowd-funding is now commonplace, while an education at film school is not.

SXSW also bears witness to a transformation in the way stuff gets consumed. Rights are now divvied up for download and streaming in the way they used to be for European territories. Theatrical and TV runs have become irrelevant to many projects, designed to be accessed online, often on the move. This means the short film is enjoying an unexpected resurgence. Mainstream film-makers are increasingly interested – Spike Jonze and Harmony Korine both have mini-movies here. The midnight shorts programme has proved one of the hottest tickets in town.

So what are the consequences? No doubt the chasm will deepen between mass entertainment film-making and the rest. Blockbuster output will likely retreat further into sequel-dominated attempts at repeat successes. And professional analysis will wither, while online sites will either cater for increasingly niche fields or focus further on celebrity and trivia. As Thompson says, even the trade papers are now covering rumours, "talks" that a star may be up for a role, rather than copper-bottomed confirmation.

Yet Hollywood can't fail to clock and then tap the innovation of amateur auteurs. Especially because, while it won't have proven brand value, its popularity will be immediately tested by virtual audience response. Purists may balk, but the likes of SXSW (and its electronic iterations) will take over from other formerly grander arenas as the hotspots for discussion of film.

Opinion at SXSW about this state of affairs is more divided than expected. Since the event is dominated by those making a go of the changing universe, there has been much applause for such a future. However, a few dissenting voices warn of a collapse into chaos in which any system of filtering films for quality is impossible, and cinema evaporates as a meaningful medium. As author Andrew Keen puts it in Press Pause Play, a documentary about "democratised culture" made by two Swedes, both under 27: "I don't think a young Fassbinder or Hitchcock would make it in this business. They would get lost in the ocean of garbage. In the global masturbation."